Bug 1441799 - Support number variant keys in BaseNode.equals (#53)

BaseNode.equals sorts order-agnostic fields such as attributes and variants in order to ensure the equality comparison works correctly even if the order of the elements differs. The code used to assume all variant keys were VariantName instances. We need to support numbers as keys as well.

Author: stasm

fluent/syntax/ast.py

@@ -103,18 +103,12 @@ def equals(self, other, ignored_fields=['span']):
                 if len(field1) != len(field2):
                     return False
 
-                # These functions are used to sort lists of items for when
-                # order doesn't matter.  Annotations are also lists but they
-                # can't be keyed on any of their fields reliably.
-                field_sorting = {
-                    'attributes': lambda elem: elem.id.name,
-                    'variants': lambda elem: elem.key.name,
-                }
-
-                if key in field_sorting:
-                    sorting = field_sorting[key]
-                    field1 = sorted(field1, key=sorting)
-                    field2 = sorted(field2, key=sorting)
+                # Sort elements of order-agnostic fields to ensure the
+                # comparison is order-agnostic as well. Annotations should be
+                # here too but they don't have sorting keys.
+                if key in ('attributes', 'variants'):
+                    field1 = sorted(field1, key=lambda elem: elem.sorting_key)
+                    field2 = sorted(field2, key=lambda elem: elem.sorting_key)
 
                 for elem1, elem2 in zip(field1, field2):
                     if not scalars_equal(elem1, elem2, ignored_fields):
@@ -255,13 +249,24 @@ def __init__(self, id, value, **kwargs):
         self.id = id
         self.value = value
 
+    @property
+    def sorting_key(self):
+        return self.id.name
+
 class Variant(SyntaxNode):
     def __init__(self, key, value, default=False, **kwargs):
         super(Variant, self).__init__(**kwargs)
         self.key = key
         self.value = value
         self.default = default
 
+    @property
+    def sorting_key(self):
+        if isinstance(self.key, NumberExpression):
+            return self.key.value
+        return self.key.name
+
+
 class NamedArgument(SyntaxNode):
     def __init__(self, name, val, **kwargs):
         super(NamedArgument, self).__init__(**kwargs)

tests/syntax/test_equals.py

@@ -119,6 +119,25 @@ def test_variants(self):
         self.assertTrue(message1.equals(message2))
         self.assertTrue(message2.equals(message1))
 
+    def test_variants_with_numbers(self):
+        message1 = self.parse_ftl_entry("""\
+            foo =
+                { $num ->
+                    [1] A
+                   *[b] B
+                }
+        """)
+        message2 = self.parse_ftl_entry("""\
+            foo =
+                { $num ->
+                   *[b] B
+                    [1] A
+                }
+        """)
+
+        self.assertTrue(message1.equals(message2))
+        self.assertTrue(message2.equals(message1))
+
 
 class TestEqualWithSpans(unittest.TestCase):
     def test_default_behavior(self):